025
FXUS65 KCYS 142023
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
223 PM MDT FRI AUG 14 2026
KEY MESSAGES
- ANOTHER ROUND OF THUNDERSTORMS WILL BRING THE POTENTIAL FOR
LOCALIZED FLASH FLOODING AND ISOLATED STRONG TO SEVERE
THUNDERSTORMS THIS AFTERNOON AND EVENING, MAINLY IN LARAMIE
COUNTY AND THE SOUTHERN NEBRASKA PANHANDLE.
- UNSETTLED WEATHER CONTINUES THROUGH AT LEAST SUNDAY, BRINGING
COOLER THAN AVERAGE TEMPERATURES AND DAILY CHANCES FOR SHOWERS
AND THUNDERSTORMS.
- ISOLATED STRONG TO SEVERE STORMS AND LOCALIZED FLASH FLOODING
WILL REMAIN POSSIBLE THROUGH SUNDAY.
- DRIER WEATHER AND TEMPERATURES CLOSE TO SEASONAL AVERAGES WILL
RETURN EARLY NEXT WEEK.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 220 PM MDT FRI AUG 14 2026
ACTIVE WEATHER CONTINUES ACROSS THE AREA AS PLENTIFUL MONSOON
MOISTURE FLOWS ACROSS THE AREA. YESTERDAY'S SHORTWAVE TROUGH PASSED
THROUGH THE AREA EARLY THIS MORNING AND BROUGHT A SLIGHTLY DRIER
AIRMASS INTO THE AREA, BUT TOTAL PRECIPITABLE WATER STILL REMAINS
ABOVE THE CLIMATOLOGICAL 90TH PERCENTILE OVER THE HIGH PLAINS.
VALUES OVER 1 INCH ARE PUSHED UP AGAINST THE LARAMIE RANGE,
INCREASING EASTWARD TO BETWEEN 1.3 AND 1.5 INCHES IN OUR FAR EASTERN
ZONES. OVERALL FORCING IS WEAKER TODAY THAN YESTERDAY, BUT WE STILL
HAVE A MORE LOCALIZED AREA OF ASCENT WHICH WILL SUPPORT STORMS, JUST
NOT QUITE AS WIDESPREAD AS YESTERDAY. WARM AIR ADVECTION IN THE
MIDDLE ATMOSPHERE IS MOVING OVERTOP A STALLED LOW-LEVEL CONVERGENCE
BOUNDARY IN LARAMIE COUNTY, WHICH WILL BE THE PRIMARY FOCUS FOR
CONVECTIVE INITIATION TODAY. RADAR ECHOES ARE ALREADY GOING UP AT
THE TIME OF THIS WRITING, AND EXPECT THIS TO CONTINUE AND GROW
UPSCALE OVER THE NEXT FEW HOURS. TODAY'S EVENT IS EXPECTED TO EVOLVE
WITH CONTINUED DEVELOPMENT IN LARAMIE COUNTY, THEN SPREADING
EASTWARD INTO THE SOUTHERN NEBRASKA PANHANDLE LATER THIS AFTERNOON
AND THROUGH THE EVENING. OUTSIDE OF THESE AREAS, ISOLATED STORMS ARE
STILL POSSIBLE, BUT TODAY'S THREAT IS FAIRLY LOCALIZED. CONVECTIVE
PARAMETERS ARE AGAIN MARGINALLY SUPPORTIVE FOR A FEW STRONG TO
SEVERE THUNDERSTORMS ALONG THE I-80 CORRIDOR REGION. MLCAPE RANGES
FROM AROUND 1000 J/KG IN LARAMIE COUNTY UP TO CLOSER TO 2000 J/KG IN
CHEYENNE COUNTY. LAPSE RATES ARE STILL FAIRLY UNIMPRESSIVE, BUT ARE
STEEPER THAN YESTERDAY. VERTICAL WIND SHEAR IS STILL MARGINAL, BUT
SUFFICIENT FOR A FEW STRONG TO SEVERE THUNDERSTORMS AT AROUND 25 TO
35 KNOTS. THE PRIMARY CONCERN TODAY REMAINS HEAVY RAINFALL AND FLASH
FLOODING, ESPECIALLY CONSIDERING POTENTIAL FOR BACK-BUILDING /
TRAINING THUNDERSTORMS AND STORMS MOVING OVER THE SAME AREAS THAT
RECEIVED HEAVY RAINFALL YESTERDAY. AS A RESULT, ANOTHER FLOOD WATCH
HAS BEEN ISSUED, AND REMAINS IN EFFECT UNTIL 10PM THIS EVENING.
ISOLATED STRONG, GUSTY WINDS AND HAIL WILL BE POSSIBLE WITH THESE
STORMS. WE WILL ALSO NEED TO WATCH FOR ACCUMULATING HAIL. EXPECT
MOST ACTIVITY TO BE GONE BY AROUND 9 TO 10 PM. A FEW SHOWERS AND
MAYBE SOME RUMBLES OF THUNDER WILL LINGER ALONG AND WEST OF THE
LARAMIE RANGE THROUGH MUCH OF THE NIGHT. LOW END POPS ARE
MAINTAINED. IN ADDITION, THE NBM REMAINS MUCH TOO COLD FOR OVERNIGHT
LOWS AS IT HAS THROUGH MOST OF THIS MONSOON SURGE, SO INCREASED
OVERNIGHT LOWS ONCE AGAIN.
LOOKING AHEAD TO SATURDAY, WE WILL HAVE ANOTHER STORMY DAY ON TAP AS
SOUTHWEST FLOW ALOFT CONTINUES TO ADVECT IN DEEP MONSOON MOISTURE.
PRECIPITABLE WATER WILL REMAIN QUITE HIGH, AROUND THE 90TH
PERCENTILE. A SHORTWAVE TROUGH ALOFT IS EXPECTED TO PULL OUT OF THE
SOUTHWEST AND MOVE ACROSS THE AREA, WHICH WILL PROVIDE BETTER
FORCING FOR LIFT WHILE ALSO INCREASING THE WIND SPEEDS IN THE MIDDLE
TO UPPER ATMOSPHERE. WITH STRONGER VERTICAL WIND SHEAR THAN THE LAST
FEW DAYS, OUR SEVERE WEATHER THREAT WILL TICK UP SOMEWHAT TOMORROW.
IN ADDITION, THE BROADER SYNOPTIC FORCING WILL LEAD TO SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS KICKING UP OVER THE EXTENT OF THE
LARAMIE RANGE, AND MOVING OFF TO THE EAST AND NORTHEAST. IT MAY BE A
FAIRLY LONG EVENING TOMORROW, WITH STORMS KICKING UP EARLY
AFTERNOON, AND POSSIBLY A SECOND ROUND INITIATING IN THE MIDDLE
EVENING HOURS AS A SECONDARY WAVE ALOFT BRINGS SOME ISENTROPIC LIFT
IN LATE.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 220 PM MDT FRI AUG 14 2026
SUNDAY...RIDGING BECOMES A BIT MORE PRONOUNCED OVER WYOMING,
PRODUCING WARMER TEMPERATURES ALOFT WHICH WILL TEND TO LIMIT AREAL
COVERAGE OF SHOWERS AND THUNDERSTORMS, COMPARED TO SATURDAY.
NEVERTHELESS THOUGH, THE MONSOONAL MOISTURE WILL STRETCH FROM
CENTRAL COLORADO THROUGH FAR EASTERN WYOMING AND WESTERN NEBRASKA,
WHERE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL
OCCUR IN THE AFTERNOON AND EVENING. SLIGHTLY WARMER, BUT
COMFORTABLE, TEMPERATURES ARE ANTICIPATED FOR THIS TIME IN AUGUST.
MONDAY...A DRIER PATTERN ENSUES AND IS ON TAP AS THE FLOW ALOFT
TURNS WEST NORTHWEST AND THE PRECIPITABLE WATER VALUES DECREASE, DUE
TO DRYING AT LOW AND MID LEVELS AND DOWNSLOPE SOUTHWEST WINDS NEAR
THE SURFACE. THUS, A MUCH DRIER DAY WHEN COMPARED TO THE WEEKEND. A
WARMING TREND BEGINS WITH MORE SUNSHINE AND WARMER MID LEVEL
TEMPERATURES NEAR 17C AT 700 MB.
TUESDAY...BRISK NORTHWEST FLOW ALOFT PREVAILS, AND WITH A DECENT
AMOUNT OF LOW AND MID LEVEL MOISTURE AVAILABILITY AS SEEN IN THE
12Z GFS RUN, EXPECT ISOLATED TO WIDELY SCATTERED LATE DAY SHOWERS
AND THUNDERSTORMS, MAINLY EAST OF INTERSTATE 25 AND THE LARAMIE
RANGE DURING THE AFTERNOON, WITH COVERAGE EVERYWHERE IN THE EVENING.
SIMILAR MAXIMUM TEMPERATURES TO MONDAY BASED ON 700 MB TEMPERATURES.
WEDNESDAY...THE SYNOPTIC PATTERN LOOKS MORE LIKE SEPTEMBER AND EARLY
AUTUMN WITH A DEEP SHORTWAVE TROUGH ALOFT SWEEPING ACROSS THE
DAKOTAS INTO WESTERN MINNESOTA BY EVENING, WITH A MUCH COOLER
AIRMASS MOVING SOUTHWARD ACROSS THE NORTHERN ROCKIES, AS WELL AS THE
NORTHERN AND CENTRAL GREAT PLAINS, INCLUDING THE DAKOTAS AND MUCH OF
NEBRASKA BEHIND A COLD FRONT. MAXIMUM TEMPERATURES FOR OUR NECK OF
THE WOODS WILL BE QUITE COMFORTABLE WITH READINGS IN THE MID 70S TO
LOWER 80S, PERHAPS EVEN COOLER THAN THIS IF THE CANADIAN COOL SURGE
LIES FURTHER WEST. FROM EXPERIENCE, AND FROM THE MODEL TRENDS, THIS
TYPE OF COLD FRONTAL PASSAGE IS TYPICALLY MOSTLY DRY FOR OUR
FORECAST AREA, AND FOR CONSISTENCY SAKE, AND MATCHING UP WITH OUR
NEIGHBORING OFFICES, WE WILL CONTINUE WITH SCATTERED SHOWERS AND
THUNDERSTORMS IN THE AFTERNOON AND EVENING FOR NOW, THOUGH SUSPECT
THAT LATER SHIFTS WILL SEE FAR LESS POPS AS MODELS COME TO MORE
CONGRUENCY AND CONSISTENCY.
THURSDAY-FRIDAY...MODELS SUGGEST A RETURN TO BONE DRY AND HOTTER
CONDITIONS AS THE RIDGE ALOFT TRANSITIONS ACROSS THE NORTHERN AND
CENTRAL ROCKIES AND OUR COUNTIES. 700 MB TEMPERATURES RISE FROM NEAR
14C AT 00Z/FRIDAY TO 18Z AT 00Z/SATURDAY YIELDING MAXIMUM
TEMPERATURES MAINLY IN THE 80S FOR THURSDAY, WITH SOME 5 TO 10
DEGREES OF WARMING FOR FRIDAY. ANOTHER HOT AND DRY PERIOD,
STRETCHING INTO THE WEEKEND,IS ON TAP.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1129 AM MDT FRI AUG 14 2026
INHERITED TAFS FROM OUR MIDNIGHT SHIFT METEOROLOGIST WERE IN
EXCELLENT SHAPE, WITH ONLY SOME MINIMAL TWEEKS NEEDED BASED ON
RECENT OBSERVATIONAL DATA AND MODEL TRENDS.
CHALLENGES INCLUDE THUNDERSTORM COVERAGE, INTENSITY, DURATION
AND CESSATION, AND SECONDARILY, THE LIKELIHOOD OF FOG AND LOW
CLOUD DEVELOPMENT LATER TONIGHT ALONG AND EAST OF THE LARAMIE
RANGE.
SOUTHWEST FLOW ALOFT PREVAILS, WITH A SHORTWAVE TROUGH ALOFT,
MOVING UP THROUGH NORTHEAST COLORADO, FAR SOUTHEAST WYOMING AND
THE SOUTHERN NEBRASKA PANHANDLE LATER THIS AFTERNOON AND THIS
EVENING, PRODUCING SCATTERED TO NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS TO THE SOUTHEAST OF A LARAMIE TO CHADRON LINE
THROUGH THE EVENING HOURS, WITH FAR DRIER CONDITIONS ELSEWHERE.
WYOMING TAFS...USING THE 12Z NAM AND THE CONSISTENT RUNS OF THE
HRRR, INCLUDING THE LATEST HRRR RUNS, HIGH CONFIDENCE IN THE
DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING, TO THE SOUTHEAST
OF A LARAMIE TO TORRINGTON LINE, WITH ENOUGH SIGNALS TO GO WITH
A TEMPO WORDING FOR KCYS FROM 20Z TO 24Z, WITH SOME STORMS
PRODUCING WIND GUSTS UP TO 48 KNOTS ALONG WITH SOME MVFR
VISIBILITIES AND LOW VFR CEILINGS. FELT CONFIDENT ENOUGH TO
INCLUDE VCTS AT LARAMIE FROM 20Z TO 01Z, AND WILL MONITOR
CUMULONIMBUS DEVELOPMENT FOR LATER UPDATES. STORMS LOOK TO
REMAIN WELL EAST OF KRWL, THUS NO MENTION OF THUNDERSTORMS
THERE.
OTHERWISE VFR PREVAILS, WITH GRADIENT AND MIX DOWN WINDS
PRODUCING GUSTS TO 35 KNOTS AT THE TAF SITES THROUGH SUNSET.
NEBRASKA TAFS...USING THE CONSISTENT RUNS OF THE HRRR, INCLUDING
THE LATEST HRRR RUNS, AS WELL AS THE 12Z NAM, THERE IS HIGH
CONFIDENCE IN THE DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS
AND SCATTERED THUNDERSTORMS THIS AFTERNOON AND THIS EVENING, TO
THE EAST OF A LINE FROM LARAMIE TO CHADRON, WITH ENOUGH SIGNALS
TO GO WITH A TEMPO WORDING FOR SCOTTSBLUFF AND SIDNEY FROM 22Z
TO 02Z AND FROM 23Z TO 03Z, AT SCOTTSBLUFF AND SIDNEY,
RESPECTIVELY, SOME STORMS AT SCOTTSBLUFF AND SIDNEY WILL PRODUCE
ERRATIC WINDS AND GUSTS TO 45 TO 50 KNOTS, WITH HIGH MVFR AND
LOW VFR CEILINGS AND VISIBILITIES AND EVEN SOME POSSIBLE HAIL.
LOCALLY HEAVY RAIN IS ANTICIPATED ACROSS THE SOUTHERN HALF OF
THE PANHANDLE LATER THIS AFTERNOON AND EVENING FROM SLOW MOVING
THUNDERSTORMS. USING THE HRRR RUNS, BEING CONSISTENT AND ALL,
FELT CONFIDENT ENOUGH TO INCLUDE A PROB30 AT KAIA FROM 23Z TO
02Z, WITH MVFR VISIBILITIES AND LOW VFR CEILINGS. NO MENTION OF
THUNDERSTORMS AT KCDR.
OTHERWISE VFR PREVAILS, WITH MIX DOWN WINDS AND GRADIENT WINDS
PRODUCING GUSTS TO 25 KNOTS AT THE SITES. BASED ON EXPECTED
RAINFALL AND BOUNDARY LAYER PROGS, AND EXPERIENCE WITH THESE
TYPES OF SYNOPTIC AND MESOSCALE SETUPS, FEEL CONFIDENT ENOUGH TO
INCLUDE IFR AND LOW MVFR CEILINGS AND VISIBILITIES IN FOG AT
ALL SITES FROM ROUGHLY 08Z TO 15Z.
CYS WATCHES/WARNINGS/ADVISORIES
WY...FLOOD WATCH UNTIL 10 PM MDT THIS EVENING FOR WYZ117>119.
NE...FLOOD WATCH UNTIL 10 PM MDT THIS EVENING FOR NEZ020-021-054-
055.
SHORT TERM...MN
LONG TERM...RUBIN
AVIATION...RUBIN
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